Lithium batteries have become useful in many commercial applications due to the high energy availability between the lithium anode and the variety of cathodes employed in lithium batteries. By far the greatest portion of the lithium battery industry, however, is in the primary active batteries. Lithium batteries have demonstrated a high degree of shelf life and these batteries are becoming accepted as reliable power sources.
However, one of the main concerns about lithium batteries is the relatively high cost of manufacture. In many instances, the high energy and substantially longer life does not justify the expense of lithium batteries. This is particularly true when alternate power sources such as rechargeable batteries can be employed. Lithium battery power cost is excessive when compared to rechargeable batteries.
In order to further develop the lithium battery industry, what is particularly needed is a lithium battery which is capable of operating on a secondary mode. Rechargeable lithium batteries would have the inherent high energy and long life capabilities of their primary versions while eliminating the excessive high cost due to replacement. One of the major problems to be solved in lithium rechargeable electrochemical power sources, however, is the improvement of electrolyte solution with suitable additives from which lithium can be deposited and dissolved and redeposited with efficiency. Stated another way, if the lithium battery cannot be recharged more than a few times and at only a relatively poor efficiency, it is not an effective substitute for other rechargeable cells. Another problem which arises in conventional prior art lithium rechargeable batteries is that the electrodeposited lithium is more reactive towards the solvent and/or the electrolyte solution than is the bulk lithium comprising the lithium electrode. Thus, the lithium recovery efficiency is very low on wet stand.
Accordingly, it is an object of this invention to provide a rechargeable lithium battery which is capable of repeated cycling with high efficiency of redeposition.
Another object of this invention is to provide a lithium battery which is rechargeable and which has an improved recovery efficiency on wet stand.
Other objects will appear hereinafter.